The present invention relates generally to a liner for the combustor of a gas turbine engine and, in particular, to an annular one-piece corrugated liner of substantially sinusoidal cross-section where the amplitude of the corrugations and/or the wavelength between adjacent corrugations is varied from an upstream end to a downstream end.
Combustor liners are generally used in the combustion section of a gas turbine engine located between the compressor and turbine sections of the engine, although such liners may also be used in the exhaust sections of aircraft engines that employ afterburners. Combustors generally include an exterior casing and an interior combustor where fuel is burned to produce a hot gas at an intensely high temperature (e.g., 3000xc2x0 F. or even higher). To prevent this intense heat from damaging the combustor case and the surrounding engine before it exits to a turbine, a heat shield or combustor liner is provided in the interior of the combustor.
One type of liner design includes a number of annular sheet metal bands which are joined by brazing, where each band is subject to piercing operations after forming to incorporate nugget cooling holes and shaped dilution holes. Each band is then tack welded and brazed to the adjacent band, with stiffeners known as xe2x80x9cbelly bandsxe2x80x9d being tack welded and brazed to the sheet metal bands. The fabrication of this liner has been found to be labor intensive and difficult, principally due to the inefficiency of brazing steps applied to the stiffeners and sheet metal bands.
In order to eliminate the plurality of individual sheet metal bands, an annular one-piece sheet metal liner design has been developed as disclosed in U.S. Pat. No. 5,181,379 to Wakeman et al., U.S. No. Pat. 5,233,828 to Napoli, U.S. No. Pat. 5,279,127 to Napoli, U.S. No. Pat. 5,465,572 to Nicoll et al., and U.S. No. Pat. 5,483,794 to Nicoll et al. While each of these patents is primarily concerned with various cooling aspects of the one-piece liner, it will be noted that alternative configurations for such liners are disclosed as being corrugated so as to form a wavy wall. In this way, the buckling resistance and restriction of liner deflection for such liners is improved. The corrugations preferably take on a shallow sine wave form, but the amplitude of each corrugation (wave) and the wavelength between adjacent corrugations (waves) is shown and described as being substantially uniform across the axial length of the liner.
It has been determined that the stiffness requirements for a one-piece sheet metal liner are likely to vary across the axial length thereof since certain points will be weaker than others. Thus, it would be desirable for an annular, one-piece corrugated liner to be developed for use with a gas turbine engine combustor which provides a variable amount of stiffness along its axial length as required by the liner. It would also be desirable for such a liner to be manufactured and assembled more easily, including the manner in which it is attached at its upstream and downstream ends.
In a first exemplary embodiment of the invention, an annular one-piece liner for a combustor of a gas turbine engine is disclosed as including a first end adjacent to an upstream end of the combustor, a second end adjacent to a downstream end of the combustor, and a plurality of corrugations between the first and second ends, each corrugation having an amplitude and a wavelength between an adjacent corrugation, wherein the amplitude of the corrugations is variable from the first end to the second end. The wavelengths between adjacent corrugations may be either substantially equal or variable from the first end to the second end of the liner.
In a second exemplary embodiment of the invention, an annular one-piece liner for a combustor of a gas turbine engine is disclosed as including a first end adjacent to an upstream end of the combustor, a second end adjacent to a downstream end of the combustor, and a plurality of corrugations between the first and second ends, each corrugation having an amplitude and a wavelength between an adjacent corrugation, wherein the wavelength between adjacent corrugations is variable from the first end to the second end. The amplitudes of each corrugation may be either substantially equal or variable from the first end to the second end of the liner.